RFID system

Abstract

A technique of reducing the interference wave occurred between a plurality of reader/writers in an environment in which a plurality of RFID systems are operating. An RFID system includes a plurality of reader/writers and a controller for controlling the plurality of reader/writers. Each reader/writer includes a body, antennas, and a distributor for selecting one antenna from the antennas. The controller selects an antenna having a positional relationship in which the interference wave is small from the antennas of each reader/writer, and giving a command for the antenna to the body of each reader/writer. Each reader/writer selects one antenna from the antennas based on the command from the controller and transmits a command to the RFID.

1 . An RFID system comprising a plurality of reader/writers for transmitting an interrogation signal to an RFID and receiving a response signal, and a controller for controlling the plurality of reader/writers;
 wherein the plurality of reader/writers each includes: a body; a plurality of antennas; and a distributor for selecting one antenna from the plurality of antennas;   the controller has a function of giving a command to each body of the plurality of reader/writers which antenna to select from the plurality of antennas of the plurality of reader/writers;   the controller selects an antenna having a positional relationship in which an interference wave is small, and giving a command for the antenna to each body of the plurality of reader/writers; and   the plurality of reader/writers each selects one antenna from the plurality of antennas based on the command from the controller and transmits the interrogation signal via the distributor.   
   
   
       2 . The RFID system according to  claim 1 ,
 wherein the respective antennas have a directivity property in which its gain become strong in one direction and weak in another direction.   
   
   
       3 . The RFID system according to  claim 2 ,
 wherein the controller selects antennas of respective reader/writers according to an antenna arrangement of each arranged reader/writer and the directivity property.   
   
   
       4 . The RFID system according to  claim 2 ,
 wherein the controller selects antennas having the same orientation from the plurality of antennas of the plurality of reader/writers as the antenna having a positional relationship in which the interference wave is small.   
   
   
       5 . The RFID system according to  claim 3 ,
 wherein the controller further has a function of: selecting a carrier wave frequency to be used for transmitting and receiving the interrogation signal and a response signal; and giving a command for the carrier wave frequency to each body of the plurality of reader/writers.   
   
   
       6 . The RFID system according to  claim 5 ,
 wherein the controller selects a carrier wave frequency to be used by each reader/writer in transmission and reception with a frequency interval set apart, and giving a command for the carrier wave frequency to the body of each reader/writer.   
   
   
       7 . The RFID system according to  claim 3 ,
 wherein the controller further has a function of: monitoring transmission and reception states of the interrogation signal and the response signal in the respective plurality of reader/writers; and giving a command for the transmission and reception timings of each reader/writer to the body of each reader/writer.   
   
   
       8 . The RFID system according to  claim 7 ,
 wherein the controller monitors the transmission and reception state of the each reader/writer to match the transmission and reception timings of each reader/writer; stops and stands by the radio communication other than that of a specific reader/writer if a time width of the transmission signal of each reader/writer differs; selects the carrier wave frequency to be used in transmission and reception; and gives a command for a carrier wave frequency to the body of each reader/writer.